The present invention relates to a laundry waste water treatment and wash process, and in particular, to such a process using ozone as a cleaning and disinfecting agent. The invention is an improvement over U.S. Pat. Nos. 5,097,556; 5,181,399 and 5,241,720 which are assigned to the assignee of the present invention. The disclosure and technologies discussed in U.S. Pat. Nos. 5,097,556; 5,181,399 and 5,241,720 are incorporated herein by way of reference.
Ozone, a gas at room temperature formed by a combination of free individual oxygen molecules, is a powerful oxidizing agent, and as such, has proven effective in the removal of odor, soil and other contamination materials from textiles. In the prior patent, a process for washing laundry using a closed-loop wash water system was disclosed in which a wash water supply is ozonated and delivered to a series of washing machines for washing laundry. The used wash water is collected at the end of the cycle and recirculated back to the storage means for re-use. The waste materials, such as soil, lint and so forth, are removed from the wash water at the end of the wash cycle prior to it being recycled back to the supply. Filtering, recirculating and replenishing wash water lost during the washing process are among the process steps disclosed in the patent.
Whereas the prior patented processes operated with some success, the machinery was too large for most commercial applications and was labor and maintenance intensive for the purpose of washing clothes, the present invention relates to an improved process for accomplishing an improved result, and in particular, to an improved efficiency in the method of generating ozone, an improved method of entraining the ozone with the wash water, and improved methods of waste removal, resulting in a more compact system design, increased automation and lower maintenance requirements. Ozone generation is greatly enhanced by the addition of an oxygen and/or dried air feed concentrator. The increased output of an oxygen allows for greater ozone production, while reducing the overall footprint associated with ozone generation equipment, thus allowing for operation in a greater number of locations with space restrictions. Furthermore, the increased output allows for dissolution of greater amounts of ozone in the water and at significantly faster rates, which allows the dissolved ozone levels to be maintained. This reduces start-up times, increases the disinfection rate, increases deodorization rates, and increases the oxidation rates of other water-borne contaminates. This will allow for smaller water storage and water contact tank sizes, which will reduce the overall footprint associated with such water containment vessels, thus allowing for installation and operation in areas with severe space limitations. Furthermore, ozone entrainment is enhanced by using a venturi injector which generates a vacuum in the flow line between the ozone generator and the venturi for the contact and storage vessels. Optionally, entrainment can further be enhanced by restricting the flow to both the storage and contact tanks, thus causing back pressure in the line carrying water. This back pressure of between 10 to 30 psi. greatly increase the dissolution rate. The venturi injector acts as a mixer when handling ozone/air mixture. STATIC MIXERS, that is, nozzles for mixing fluid materials, may or may not be placed after the venturi for additional turbulence. Ozone contact extenders can be added to increase ozone contact time with the water, which also increases the dissolution rate. These extenders may or may not be fitted with STATIC MIXERS to enhance entrainment. Furthermore, increased output of the oxygen and/or dried air ozone generator can reduce or eliminate the need for an ozone contact extender in locations where maximum dissolution is not as critical as space conservation, thus allowing for a reduction in the footprint associated with contact extenders and associated plumbing. The ozone generator may be equipped with an optional voltage regulator so that ozone levels may be increased or decreased according to need. Specifically, this regulation is applied daily in the initial start-up phase of the system or when ozone demand in the system increases due to large amounts of water-borne contaminants. This would allow greater flexibility when processing clothes or water of a heterogeneous nature.
The present invention also includes the process of tiered filtration. Starting with a coarse screen or bag filter, large particles of lint and other materials are removed. This is followed by a filter or filters designed to remove still finer particles. The storage tank then can be used as a floatation chamber, wherein sufficient back-pressure is applied to ozone gas being pumped into the tank. This will cause the creation of millions of effervescent bubbles which will float dissolved solids to the top of the storage tank where they can be removed by overflowing the tank, forcing the floated solids up and over a weir at the top of the tank. This can be followed by one or more polishing filters designed to remove even finer particles in the wash water.
Other new features include the optional use of a water softener to remove hardness from the local water supply. This feature decreases the time associated with charging the make-up water as it is added. Another feature is the optional recycling of off-gas from the top of the contact tank and entraining it into the storage tank. This reduces the total amount of ozone that needs to be generated and reduces the amount of ozone that needs to be vented and/or destroyed.
Among the objects of the present invention are the provision of an improved laundry waste water treatment system using ozone for cleaning and decontamination of laundry materials, which saves water, reduces or eliminates the need for hot water, soap and chemicals, and greatly reduces the cost of operation.
Another object is the provision of an improved laundry treatment system which utilizes a neutral to slightly basic pH, which favors hydroxyl radical (OH.cndot.) production to promote advanced oxidation chemistry in combination with ozone to enhance the cleaning process.
A still further object of the present invention is the provision of a laundry wash system using generated ozone entrained in the wash water having an improved ozone entrainment system to increase the efficiency of the ozone wash process.
A still further object of the present invention is the provision of a laundry wash system using oxygen and/or dried air generated ozone entrained in the wash water having an increased ozone production to increase the efficiency of the ozone wash process, cleaning the contaminated water, reducing the overall size, and increasing reliability.
A still further object of the present invention is the provision of a laundry wash system using contact extenders, where desirable, to increase contact time between the ozone and the wash water resulting in an increase in the ozone dissolution rate and the maximum ozone concentration that can be maintained.
A still further object of the present invention is the provision of a laundry wash system using contact extenders fitted with static mixers, where desirable, to increase the mixing between the ozone and the wash water having an increase in the ozone dissolution rate and the maximum ozone concentration that can be maintained.
A still further object of the present invention is the provision of a laundry wash system using flow restriction to create back-pressure in the effluent side of the venturi plumbing thus causing a percentage of the ozone gas to become dissolved in the process water, thus increasing the ozone dissolution rate and the maximum ozone concentration that can be maintained.
A still further object of the present invention is the provision of a laundry wash system using flow restriction to create back-pressure causing a percentage of the ozone gas to become dissolved in the storage water which can be used to float waste materials to the top of the storage means where upon an overflow of water can carry said waste material to drain. A still further object of the present invention is the provision of a laundry wash system using a tiered filtration system where in a coarse filter is applied first to remove lint and other large debris, followed subsequently by increasingly finer filtration, including floatation of dissolved and suspended solids, before water is recycled and used again.
A still further object of the present invention is the provision of a laundry wash system which recycles, where desirable, the off-gas of the contact means for use in the storage means. In addition, increased back-pressure can be applied in the recycling of the ozone off-gas, which will reduce the amount of total off-gas the system will produce.
A still further object of the present invention is the provision of a laundry wash system using sloped bottom tanks to allow for complete draining of the tank and/or particle draining to remove waste materials which have settled.
A still further object of the present invention is the provision of a laundry wash system using sloped lids on the tanks to allow for an overflow cycle, wherein the water level is raised, forcing the floated particles and debris into or over a removal weir.
A still further object of the present invention is the provision of a laundry wash system using, optional, a polishing filter (able to filter the most minute particles) as to ensure the utmost water quality in the most demanding situations.
A still further object of the present invention is the provision of a laundry wash system using dissolved air floatation (DAF) technology to further clean the wash water and greatly increase the water recycling capability.
These and other objects will become apparent with reference to the following drawings and specification.